A service switching device of this generic type normally has a contact point which is formed by a fixed and a moving contact piece, with the moving contact piece being held on a contact lever which is mounted such that it can pivot. A service switching device of this generic type furthermore has a magnetic release with a magnet armature and a thermal release, as well as a switching mechanism, which can be tripped by the thermal and the magnetic release and has a latching point. This is formed by a tripping lever and a catch lever which is mounted in a fixed position such that it can rotate and has a elongated hole for guiding a clip. In the event of a short, the magnet armature can act on the contact lever, to which the moving contact piece is fitted, in order to open the contact point, and the switching mechanism can hold the contact lever permanently open. Furthermore, a service switching device of this generic type has a switching toggle for manual operation of the switching mechanism, and an intermediate lever, which is articulated at one of its ends with the contact lever and at its other end on the clip, with the clip being articulated by at least one limb on the switching toggle.
In service switching devices of this generic type, the force of a contact compression spring acts on the contact lever and is passed to the contact lever such that, when in the connected position, it presses the moving contact piece against the fixed contact piece, and in the disconnected position presses the moving contact piece away from the fixed contact piece.
The intermediate lever in this case represents the linking element between the switching mechanism and the contact lever.
In the connected position, the contact lever is held by the intermediate lever, which is blocked by the switching mechanism. A first, moving rotation point of the contact lever is blocked in a first position by the latched switching mechanism, such that the contact compression spring can press the contact lever against the fixed contact piece, around the first rotation point.
In the tripped or disconnected position, the intermediate lever is released from the switching mechanism. The switching mechanism is unlatched and releases the first rotation point of the contact lever, so that the contact compression spring can press the contact lever to the open position around a second fixed-position rotation point, in which open position the moving contact piece is at a distance from the stationary contact piece.
During thermal or short-circuit current disconnection, the switching mechanism is unlatched by the thermal or the electromagnetic release, acting on a tripping lever such that it can move from the connected state to the disconnected state. In the event of electromagnetic quick tripping, the magnet armature additionally knocks the moving contact lever away directly in order to quickly open the contact point, because disconnection by means of the unlatched switching mechanism would be slower than would be permissible for quick tripping, because of the mechanical inertia of the components involved.
Service switching devices of this generic type are known in which the switching mechanism is mounted with the contact lever in a prefabricated assembly between two boards, and can be inserted as an entity into the appliance while the appliance is being assembled. A tripping slide must then also be inserted after this, in order to couple the switching mechanism to the thermal and/or the magnetic release. EP 0144799 A1 discloses on example. Manufacturing tolerances during assembly of the board can in this case result in movements and tilting between the individual levers of the switching mechanism. When the contact lever is struck by the quick release during short-circuit tripping, then it strikes against a stop within the boards, so that the board parts can be moved further away from one another and, over time, the play between the various levers in the switching mechanism can become too great for precise operation. This can result in a lack of shape and position stability of the contact lever. Furthermore, the manufacture of the switching mechanism is quite complex, and it is costly to manufacture because of the sensitive tolerances and the riveted joints.
DE 10 2004 055 564 A1 discloses a service switching device having a switching mechanism whose individual parts are inserted successively into the housing, together with the contact lever. The switching mechanism with the contact lever is in this case no longer inserted as a prefabricated assembly but, so to speak, it grows within the housing. The thermal release and the contact lever are located on different sides, with respect to the magnetic release, so that, in this case as well, a tripping slide can be inserted separately, as an extension of the switching mechanism, between the thermal release and the switching mechanism.
This design is intended to be suitable for completely automatic manufacture that requires high-precision feeding and positioning of a large number of individual parts, thus making the automation production facilities highly complicated and expensive.